The present invention relates to biodegradable hyaluronic acid filler compositions for soft tissue implants such as dermal fillers or breast, butt, or body implants.
Young, healthy-looking skin contains an abundance of a naturally hydrating substance called hyaluronic acid (HA). But as people age, sunlight and other factors can reduce the amount of HA in their skin. The lack of HA causes skin to lose structure and volume, creating unwanted facial wrinkles and folds—like those parentheses lines around the nose and mouth. Injectable dermal implants are a popular solution to a wide variety of facial contour defects from lip augmentation to plumping up depressed scars. Often used as tissue replacement for victims of serious accidents, injectable dermal implants are very effective in cosmetic surgery procedures such as lip augmentation and scar removal. Using a dermal filler is a safe and effective way to replace the HA the skin has lost, bringing back its volume and smoothing away facial wrinkles and folds.
In a parallel trend, millions of women have undergone breast, butt, or body augmentation and reconstruction in the past few decades. Most women choose augmentation to enhance the size and shape of one or both breast, butt, or bodys for personal or aesthetic reasons. In contrast, women who undergo a reconstruction procedure want to reconstruct a breast, butt, or body that has been removed, typically for health reasons, such as tumor removal. The reconstruction procedure may vary from a modified radical mastectomy (removal of the underlying muscle as well as the breast, butt, or body part), to a simple mastectomy (removal of one breast, butt, or body part), to a bilateral mastectomy (removal of both breast, butt, or body parts) or to a lumpectomy (removal of a portion of the breast, butt, or body part). In either augmentation or reconstruction, the modality intimates the surgical implantation of a breast, butt, or body prosthesis (implant).
Conventional implants for treating breast, butt, or body augmentation or reconstruction include a shell or envelope that is filled with a filler composition, for example, silicone gel, saline solution, or other suitable filler. It is desirable that the filler have lubricating properties to prevent shell abrasion, remain stable over long periods of time, be non-carcinogenic and non-toxic, and have physical properties to prevent skin wrinkling, capsular contracture formation, and implant palpability.
In response to the failures of saline and silicone-gel implants, there have been a number of attempts to make a prosthesis filled with a non-toxic filler that that mimics the shape and feel of a natural breast, butt, or body provided by silicone-gel yet is safe to the immune system like saline. Other attempts to provide a safe filler material include polyethylene glycol. However, the triglyceride oil or honey fails to provide an implant that is aesthetically pleasing and also duplicates the touch and feel of a natural breast, butt, or body due to the low viscosity of the fillers. Due to the limited options and the inadequacy of current fillers to achieve the desired results, there is a need for safe and efficacious fillers.
In one trend, hyaluronic acid (HA) has been steadily gaining popularity in the area of aesthetic medicine because of its ubiquity and biocompatibility. HA has been limited to small areas such as nasal labial folds, lips and glabella lines to name a few. However, if the HA is cross linked in-vitro, the non-Newtonian nature of the HA cross linked gel makes it very difficult to augment larger anatomical spaces in a minimally invasive fashion.